A problem I encountered years ago with Windows updates now happens on the iDevices, where you purchase wifi MBs at a motel/hotel and they vanish incredibly fast.

With the iDevices (iPad, iPhone) by default auto updating when connected to wifi you'll find that an update flurry can suck all the bandwidth you have just purchased. So before you activate the purchased MBs dive into settings, scroll to iTunes and App Store and under Automatic Updates turn them all off.

Like in the old days before the last iOS Update you'll get the badge on the App Store icon showing updates are available and you can manually update the ones you want to, or wait until you're back to your wifi and turn the auto updates back on.

Recently Purchased 150mb at a motel and it disappeared within 1/2 hr of connecting.